std::span is not present on remote containers Follow

Since I am working on a 2020 macbook air, I have setup a remote environment with docker in order to be able to use valgrind, by following this tutorial: https://www.jetbrains.com/help/clion/clion-toolchains-in-docker.html

I am using c++ 20, and have tested several c++20 features on the remote container, which seem to work well, namely likely attributes and range-based for loop initializers. The -std=c++20 and -std=c++2a flags seem to be working fine on clang and gcc respectively.

However, I have not been able to make std::span work and get the following error when I try to #include <span>: "fatal error: 'span' file not found".  Is there any way to get the file on the container? 

Any help would be appreciated, thank you.

Edit: I am using the ubuntu Dockerfile that's provided by JetBrains at https://github.com/JetBrains/clion-remote